From the Veterans Affairs Western New York Healthcare System (AAE, AH), Western New York Respiratory Research Center, Division of Pulmonary, Critical Care, and Sleep Medicine (AAE, AH, AA, HV), Department of Medicine, Department of Anesthesiology (AAE), University at Buffalo School of Medicine and Biomedical Sciences, Buffalo, NY; and Department of Microbiology and Immunology (ARH), Feinberg School of Medicine, Northwestern University, Chicago, IL.